Her death comes three months after a man was cautioned for sending her “malicious communications”, but police have confirmed this was not the same man who was arrested on Thursday following the attack.

Witnesses said her assailant kicked and stabbed her and then shot her several times, the final shot aimed at her head.

Politicians have been warned to review their security following the horrific killing.

A reminder of safety guidance, which includes steps representatives can take to stay safe when they are “out and about” and suggests if they have any concerns they should contact their local police, has been issued, No 10 said.

The alleged gunman has been named locally as Tommy Mair, 52, who neighbours in Birstall have described as “a loner”. He was arrested near the scene soon after the attack.

The MP’s husband Brendan said: “Today is the beginning of a new chapter in our lives. More difficult, more painful, less joyful, less full of love.

“I and Jo’s friends and family are going to work every moment of our lives to love and nurture our kids and to fight against the hate that killed Jo.

“Jo believed in a better world and she fought for it every day of her life with an energy and a zest for life that would exhaust most people.

“She would have wanted two things above all else to happen now: one, that our precious children are bathed in love, and two, that we all unite to fight against the hatred that killed her.

“Hate doesn’t have a creed, race or religion, it is poisonous.

“Jo would have no regrets about her life, she lived every day of it to the full.”

Mr Corbyn said the country would be “in shock at the horrific murder” of a “much-loved colleague”.

In Mrs Cox’s home town, hundreds of people, including Labour colleagues Yvette Cooper and Dan Jarvis, packed into the parish church to hear the Bishop of Huddersfield, the Rt Rev Dr Jonathan Gibbs, pay tribute to someone who “gave her life for this community”.

Mr Cameron said: “The death of Jo Cox is a tragedy. She was a committed and caring MP. My thoughts are with her husband Brendan and her two young children.”

Flags across Whitehall are flying at half-mast, while flags at Buckingham Palace and the Palace of Holyroodhouse in Edinburgh are also being lowered in tribute.

A Buckingham Palace spokesman said the Queen had written privately to Mr Cox.